There has so far been known a liquid crystal projector for forming an image light beam by light modulation of light, output from a light source, with e.g. a transmissive liquid crystal panel, and for projecting the so formed image light beam on e.g. a screen. With this liquid crystal projector, light modulation is effectuated by liquid crystal panels, associated with three prime color light beams of red (R), green (G) and blue (B), and the respective light beams, formed by this light modulation, are synthesized together to output a full-color image.
A liquid crystal projector for eliminating irregularities in a picture image and for improving the contrast by widening the viewing angle of a liquid crystal panel has been proposed in JP Laid-Open Patent Publication 2001-42314. The liquid crystal projector, disclosed in this Laid-Open Patent Publication, includes a lamp 102 including a light emitting unit 102b at a focal point position of a reflector 102a, as shown in FIG. 1. A light beam, radiated from the lamp 102, is radiated forwards from an opening part of the lamp as a light beam substantially parallel to the optical axis of the reflector 102a. 
On a downstream side stage of the lamp 102, there are arranged a multi-lens array 103, made up of a plural number of lens cells, arranged in, for example, a square array, and another multi-lens array 104. An envelope of the lens cells of the multi-lens array 103 is of a shape and an aspect ratio similar to those of an irradiated area of a liquid crystal panel, formed of, for example twisted nematic liquid crystal, and making up liquid crystal panel sections 110, 113, 119, which will be explained later. The other multi-lens array 104 is made up of a plural number of lens cells, arranged facing the lens cells of the multi-lens array 103. The light beam collected by the multi-lens arrays 103, 104 is turned into a polarized light beam of a predetermined direction of polarization by a light polarization block 105. That is, the unpolarized light, i.e. P-polarized light plus S-polarized light, radiated from the lamp 102, is passed through the light polarization block 105 and thereby converted into a light beam of a predetermined direction of light polarization, for example, P-polarized light, for matching with the liquid crystal panel sections 110, 113, 119. Meanwhile, the explanation on the light polarization block 105 is dispensed with.
The light converted into, for example, the P-polarized light beam, by the light polarization block 105, falls on a plano-convex lens 106, arranged next to the light polarization block 105. This plano-convex lens 106 is configured for collecting the light beam from the light polarization block 105 for efficiently illuminating the liquid crystal panels.
The light beam radiated from the plano-convex lens 106, that is, the white light, initially falls on a dichroic mirror 107, adapted for transmitting a red light beam R. The dichroic mirror transmits the red light beam R and reflects a green light beam G and a blue light beam B. The red light beam R, transmitted through the dichroic mirror 107, has its proceeding direction bent by e.g. 90° by a mirror 108, and is routed to a liquid crystal panel section 110 via a plano-convex lens 109.
On the other hand, the green light beam G and the blue light beam B, reflected by the dichroic mirror 107, are separated from each other by a dichroic mirror 104 adapted for transmitting the blue light beam B. That is, the green light beam G is reflected by the dichroic mirror 104 and routed to the liquid crystal panel section 113 through a plano-convex lens 112. The blue light beam B is transmitted through the dichroic mirror 104 and proceeds rectilinearly to get to the liquid crystal panel section 119 through a relay lens 114, a mirror 115, a relay lens 116, a mirror 117 and a plano-convex lens 118.
The light beams of the respective colors, light-modulated by the liquid crystal panel sections 110, 113, 119, are incident on a cross-prism 120, which cross-prism 120 is formed by joining plural glass prisms together. On the junction surfaces of the glass prisms are formed interference filters 121a, 121b having preset optical characteristics. For example, the interference filter 121a is constructed to reflect the red light beam R and to transmit the green light beam G, while the interference filter 121b is constructed to reflect the blue light beam B and to transmit the green light beam G. Hence, the red light beam R is transmitted through the interference filter 121a, while the blue light beam B is transmitted through the interference filter 121b, so that both light beams get to a projection lens 122, where the respective light beams are synthesized on a sole optical axis.
With the above-described liquid crystal projector 100, such a problem arises that the contrast is lowered depending on the viewing angle. This problem, concerned with the viewing angle, may be attributable to the twist of the twisted nematic liquid crystal molecules that make up a liquid crystal panel, as shown in FIG. 2. In this figure, there is shown an array of liquid crystal molecules of a normally white liquid crystal panel 132 arranged between light polarizing plates 130, 133. An arrow indicated by a solid line in each of oriented films 132a, 132b indicates the direction of processing for alignment. If a driving voltage is applied to the liquid crystal panel 132, constructed as described above, liquid crystal molecules are set upright, from the state shown, such as to shut off any incident light beam. On an interface of each of the oriented films 132a, 132b, the direction of alignment of liquid crystal molecules has a preset angle relative to the direction of processing for alignment. This preset angle is termed a pre-tilt angle. This preset angle is the angle of molecular alignment initially afforded to the direction of processing for alignment for guiding the driving direction of the liquid crystal molecules on application of a driving voltage. By applying the driving voltage to the liquid crystal panel 132 to set the liquid crystal molecules upright, it becomes possible to display the black level. However, the light blocking performance related with the viewing angle is deteriorated under the above-mentioned effect of the pre-tilt angle to produce the phenomenon of whiting of black color to lead to contrast deterioration.
Hence, in the conventional liquid crystal projector 100, a phase difference film 131 is arranged between the light polarizing plate 130 and the liquid crystal panel 132 to improve the contrast, as shown in FIG. 3. In the liquid crystal panel 132, shown in FIG. 3, a first light polarizing plate 130, arranged on the light incident side, has an axis of polarization, that is, the direction of polarization, along the z-axis, for example. Hence, the light beam passed through the light polarizing plate 130 gets to the phase difference film 131. This phase difference film 131 is arranged so that a retarded phase axis or a fast axis thereof crosses the axis of light polarization of the light polarizing plate 130. In addition, the phase difference film 131 is arranged at a preset angle of tilt about an axis of rotation which is contained in a plane of the phase difference film 131 and which extends parallel to the axis of light polarization of the light polarizing plate 130. As for the liquid crystal panel 132, the direction of processing for alignment of the orienting film 132a is the x-axis direction, while that of the orienting film 132b is the y-axis direction, as in the case shown in FIG. 2. The liquid crystal molecules are oriented with a required pre-tilt angle, as indicated by thick bars entered in the figure in connection with the orienting films 132a, 132b. Hence, an angular difference corresponding to the aforementioned preset pre-tilt angle exists between the axis of light polarization of the light polarizing plate 130 and the direction of alignment of the liquid crystal molecules. The phase difference film 131 corrects this angular difference so that the phase of the light beam transmitted through the light polarizing plate 130 is in keeping with the array of the liquid crystal molecules of the orienting film 130a having the pre-tilt angle.